In recent years, high-power and downsized semiconductor device modules with high reliability have been sought as in-car power semiconductor devices. To realize these, a direct lead bonding (DLB) structure for directly bonding a power device to an external leading electrode has been introduced. Furthermore, a study has been conducted on a semiconductor device module having a direct cooling structure and combined with a finned heat sink.
When the direct cooling structure is used, a structure of packaging a plurality of power devices as one module is desired to facilitate seal design of a cooling unit and also connection to an external wire.
In the DLB structure, the reliability of the module is affected by the shape of a brazing filler metal for bonding a power device to a lead electrode, an amount of thermal displacement of the lead electrode, and the adhesion of a sealing material to each component. Thus, the shape of the brazing filler metal and the adhesion of the sealing material need to be kept in good condition to improve the reliability of the module.
Manufacturing the high-output semiconductor devices requires arranging a plurality of power devices in parallel while upsizing the individual power devices, which upsizes not only the lead electrodes but also the packages. Thus, the challenge to obtain a favorable shape of the brazing filler metal is to improve alignment precision of a lead electrode and a power device.
Since the upsized packages increase the cost of pressure sealing with a mold resin, etc., a sealing structure of inserting one side of a lead electrode into a resin case and filling the resin case with an epoxy-based resin or a silicon-based resin is frequently used as disclosed in, for example, Patent Document 1. Here, the lead electrode is cantilevered. Thus, the thermal displacement of the electrode will be presumably larger due to the heat generated in, for example, a power device. In addition, disuse of the pressure sealing makes it difficult to reduce the thermal displacement of the lead electrode, which may increase the stress to the power device and reduce the reliability of the semiconductor device module.